How do I get these matrix dimensions to match using linspace?

I am trying to write an audio algorithm to ramp up the amplitude of a .wav file but I am having problems getting getting the matrix dimensions to match in this line:

    processed_waveform = input_waveform.*linspace(0, 1, length(input_waveform));

The error reads as follows:

Error using  .* 
Matrix dimensions must agree.

Error in Ex_1D (line 41)
        processed_waveform = input_waveform.*linspace(0, 1, length(input_waveform));

I have tried using size() in place of length() but I still get the same issue. Any ideas? Thanks

Answer 1

[Star Strider]

Most audio files are column vectors, and linspace produces a row vector.

Try this:

processed_waveform = input_waveform.*linspace(0, 1, length(input_waveform))';

Transposing the linspace vector should make them compatible. If ‘input_waveform’ is a two-column matrix (two-channel sound file), the code becomes:

processed_waveform = input_waveform.*[linspace(0, 1, length(input_waveform))', linspace(0, 1, length(input_waveform))'];

[dpb]

I've long thought (and made the suggestion at least once as enhancement request) TMW should enhance this error message to explicitly note the orientation mismatch as a possbility when size(OP1)==size(OP2).' as the error occurs so often and the present missive, while correct, clearly doesn't provide guidance enough in many (most?) cases...

[Star Strider]

Allowing a size argument that would automatically orient and replicate the resulting vector would be helpful, but we’re not there yet.